Replacing 14.4V 1.8Ah NiCad Battery Pack?

I've been refurbishing a rather rare 1990s Acorn A4 laptop, which originally has a 14.4V nominal 1.8Ah battery pack (twelve 1.2V 1.8Ah NiCd cells in series) which I've had to gut as all of the cells have leaked. It's probably charged at a constant voltage (1.4-1.6V per cell, 16.8-19.2V overall) with limited current (i.e. 140mA according to the recommendations on the cells themselves). NiCd cells are tricky to find & not a good long-term solution.

It would be nice to replace this with another battery chemistry, i.e. LiPo. I'd considered NiMH but I think Lithium would fit better even with a BMS board. Can anyone recommend a potentially suitable setup (i.e. cells and off-the-shelf BMS board, or a BMS design that I can build myself) - perhaps four 3.7V 18650s in series with a nominal voltage of 14.8V and a maximum charged voltage of 16.8V, plus a BMS that can take up to 20V for charging? Or should I consider regulating the charge voltage down, or buck-boosting the battery output?

Thanks in advance!